Polietilen Tereftalat Glikol (PETG) Malzeme Kullanılarak Eklemeli İmalat Yöntemi ile Elde Edilen Honeycomb ve T-Rib Kafes Yapıların Çekme Dayanımlarının Araştırılması

Öz

Hedef parçaların, geleneksel yöntemlerdeki gibi malzemeyi kesmek, oymak veya çıkarmak yerine, eklenerek oluşturulduğu "Eklemeli İmalat (Eİ)", sağladığı tasarım özgürlüğü ile her geçen gün daha da önem kazanmaktadır. Bu yöntem, geleneksel yöntemlerle elde edilemeyen karmaşık geometriler, içi boş yapılar, kafes yapılar imalatında benzersiz avantajlar sunar. Fused Deposition Modelling (FDM), imalat için çeşitli termoplastik polimer malzemelerin kullanıldığı en yaygın eklemeli imalat yöntemidir. Polietilen Tereftalat Glikol (PETG) da yüksek darbe dayanım, kimyasal direnç ve işlenebilirlik gibi avantajları sayesinde FDM yönteminde yaygın olarak tercih edilen bir termoplastiktir. Bu çalışma, FDM yöntemi ve PETG malzeme kullanılarak imal edilen Honeycomb ve T-rib kafes yapıların mekanik özelliklerini incelemektedir. Honeycomb ve T-rib kafes yapılar hafiflik, enerji emilimi ve özelleştirilmiş mekanik özellikler sunarak çeşitli mühendislik uygulamalarında kullanılmaktadır. Kafes yapılar, hafiflik ve yüksek mukavemet avantajlarıyla mühendislik uygulamalarında önemli bir yere sahiptir. Genel olarak, kafes yapıların katman kalınlığı ve baskı sıcaklığı, baskı hızı gibi imalat parametrelerinin, mekanik özellikleri üzerinde önemli etkileri olduğu bilinmektedir. Çalışmanın birinci aşamasında 0,8mm ayrıt genişliğine ve 4mm ayrıt boyuna sahip sözü edilen farklı iki kafes yapı CAD programı ile tasarlandı. Ardından tasarımlar, ISO 527-2-2012 standardında belirtilen çekme numunesi ile bilgisayar ortamında birleştirilerek farklı iki kafes yapıya sahip çekme numuneleri ve standartta verilen ölçülerde tam dolu bir çekme numunesi oluşturuldu. İkinci aşamada, tasarımları tamamlanan çekme numuneleri PETG filament kullanılarak FDM yöntemiyle %100 doluluk oranı, 0,4mm nozul çapı, 0,18mm katman kalınlığı, 90mm/s baskı hızı, 70 °C tabla sıcaklığı ve 235 °C baskı sıcaklığı ile imal edildi. Çalışmanın üçüncü aşamasında, numunelere ISO 527-2-2012 standardında belirtildiği gibi 1mm/dak hız ile çekme testi uygulanarak, Honeycomb ve T-Rib kafes yapıların akma gerilmesi, en büyük çekme gerilmesi ve çekme elastisite modülü değerleri belirlenip kendi aralarında kıyaslandı. Çalışmanın sonunda Honeycomb’un akma gerilmesi (6,9 MPa), en büyük çekme gerilmesi (7,11 MPa) ve çekme elastisite modülü (332,49 MPa) değerlerinin; T-Rib’in akma gerilmesi (14,6 MPa), en büyük çekme gerilmesi (15,94 MPa) ve çekme elastisite modülü (634,60 MPa) değerlerinden küçük olduğu belirlendi. Kafes yapıların ayrıt genişlik ve uzunlukları her ne kadar aynı olsa da boşluk oranları arasında geometri farklılıklarından kaynaklanan bir fark olduğu görüldü. Öte yandan, her iki kafes yapıyı oluşturan birim hücrelerin ayrıt genişliklerinin ve uzunluklarının aynı olmasına rağmen birim hücrelerin geometrik farklılıklarının, akma gerilmesi, en büyük çekme gerilmesi ve çekme elastisite modülü değerlerinin farklı olmasında önemli bir etken olduğu belirlendi.

Anahtar Kelimeler

• Eklemeli imalat
• FDM
• Kafes yapı
• PETG

Investigation of Tensile Strengths of Honeycomb and T-Rib Lattice Structures Obtained by Additive Manufacturing Method Using Polyethylene Terephthalate Glycol (PETG) Material

Öz

Additive Manufacturing (AM), a production method where target parts are fabricated by adding material rather than cutting, carving, or removing it as in traditional methods, has been gaining increasing prominence due to the design flexibility it offers. This technique provides unique advantages in the fabrication of complex geometries, hollow structures, and lattice frameworks that are unattainable through conventional manufacturing methods. Among AM techniques, Fused Deposition Modelling (FDM) is the most widely utilized, employing a variety of thermoplastic polymer materials. Polyethylene Terephthalate Glycol (PETG) is a thermoplastic polymer commonly used in the FDM process owing to its high impact resistance, chemical resistance, and ease of processability. This study investigates the mechanical properties of Honeycomb and T-rib lattice structures fabricated via the FDM process using PETG material. Honeycomb and T-rib lattices are widely employed in various engineering applications due to their lightweight nature, energy absorption capabilities, and customizable mechanical performance. Lattice structures are particularly valued in engineering applications for their combination of low weight and high strength. It is well established that manufacturing parameters such as layer thickness, printing temperature, and printing speed significantly influence the mechanical performance of such structures. In the first phase of this study, two distinct lattice structures with an edge width of 0.8 mm and an edge length of 4 mm were designed using computer-aided design (CAD) software. These designs were then integrated into tensile specimens conforming to the ISO 527-2:2012 standard, resulting in tensile test samples comprising two different lattice structures, along with a fully solid tensile specimen designed according to the standard dimensions. In the second phase, the finalized designs were fabricated using the FDM process with PETG filament, employing the following parameters: 100% infill density, 0.4 mm nozzle diameter, 0.18 mm layer thickness, 90 mm/s printing speed, 70 °C build platform temperature, and 235 °C extrusion temperature. In the third phase, tensile tests were conducted on the specimens at a crosshead speed of 1 mm/min, in accordance with ISO 527-2:2012. Yield strength, ultimate tensile strength, and tensile modulus values were obtained for the Honeycomb and T-rib lattice structures, and a comparative analysis was performed. The results revealed that the Honeycomb structure exhibited lower values for yield strength (6.9 MPa), ultimate tensile strength (7.11 MPa), and tensile modulus (332.49 MPa) compared to the T-rib structure, which exhibited yield strength (14.6 MPa), ultimate tensile strength (15.94 MPa), and tensile modulus (634.60 MPa). Furthermore, despite having identical edge widths and lengths, a difference in the void ratio between the two lattice structures was observed, attributed to geometric variations. It was also determined that the geometric differences between the unit cells, despite identical edge dimensions, had a significant influence on the observed variations in yield strength, ultimate tensile strength, and tensile modulus.

Anahtar Kelimeler

• Additive manufacturing
• FDM
• Lattice structure
• PETG

Kaynakça

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